Hello itojun,
[EMAIL PROTECTED] wrote: > >> we never know what the future operators will do, so it is safer > >> not to make assumptions. > >In that case, I think we have to do something to avoid doing DAD > >for all those prefixes. One solution would be to just do it for > >link-local prefixes, which according to Dave Thaler's argument > >then become subnet-local prefixes. > > i don't think it necessary to do anything about DAD. we perform DAD > (not DIIDD) for all addresses assigned, and we will be fine. Do you still think that is true if the mobile node has to send out 10, or some unbounded number, of Binding Updates each time it changes its care-of address? The discussion in the mobile-ip group is whether a single Binding Update can suffice for all home addresses of a mobile node that share the same interface ID. This led to discussion about DAD. The subjects are not inseparably intertwined, but there is a relationship. It has been my understanding that a home agent, charged with the protocol responsibility for defending the addresses of 4,095 mobile nodes (or, say, 500,000 for some cellular plans), would effectively disable the ability of mobile nodes to use multiple prefixes, because equipment vendors would just "say no" if they thought only a few mobile nodes would use this feature. Thus, I thought that it would be a lot better to have a very simple scaling mechanism that would still allow for a large number of prefixes. This is simple, if the home agent can just defend the link-local prefix. It's not so simple if any increase in the number of advertised prefixes requires a linear increase in storage or performance requirements at the home agent. It's really quite bad if the communication requirement at the mobile node experiences a linear increase in capacity requirement at handover time. My guess is that it will just effectively mean people will not use multiple prefixes for mobile nodes. Regards, Charlie P. -------------------------------------------------------------------- IETF IPng Working Group Mailing List IPng Home Page: http://playground.sun.com/ipng FTP archive: ftp://playground.sun.com/pub/ipng Direct all administrative requests to [EMAIL PROTECTED] --------------------------------------------------------------------
